A substrate of this nature is known from German Patent Application DE-196 01 358, and is used in security documents and banknotes to protect against forgery and fraud. This known substrate comprises an integrated circuit which is incorporated in the substrate and contains predetermined data. The IC is contactlessly readable and is joined to the substrate in a non-releasable manner. The IC which is used in this substrate is a conventional IC, i.e. of the well-known silicon type. The dimensions of the chip originally produced are reduced by means of etching or polishing, so that the chip acquires the thickness which is desired for it to be incorporated in the paper mass. In order to prevent damage to the crystalline circuits, the IC is reinforced with the aid of a support layer, which also serves to position the IC. Furthermore, the IC is covered with a protective, chemically resistant layer. The lack of flexibility of this known silicon chip is a drawback when a substrate of this nature is used as a security paper, for example in banknotes and identity documents. In addition, the extra layers which are to be included, as well as the additional processing step for producing the appropriate dimensions, lead to an additional increase in the cost price of a substrate of this nature.
The object of the present invention is to provide a paper-based substrate for use in security documents, banknotes and the like, in which an integrated circuit is incorporated, which substrate does not have the drawbacks mentioned above.